The present invention relates to a belt for a continuously variable transmission, in which a pair of left and right ring slots defined in each of a plurality of metal elements are supported on a pair of left and right metal ring assemblies with each formed of a plurality of endless metal rings laminated one on another, respectively, and which is wound around a drive pulley and a driven pulley to transmit a driving force.
A belt for the continuously variable transmission suffers from the following problem: When left and right V-faces of the metal element receive an axial load from the V-grooves of the pulley, if the V-faces of the metal element are moved in an inclined manner rather than in parallel by the load, one end of the V-face is brought vertically into strong contact with the V-groove and as a result, the other end is lifted from the V-groove of the pulley, whereby an uneven wearing occurs in the metal element and the pulley.
Therefore, the inventor has proposed a belt for a continuously variable transmission in Japanese Patent Application No.2000-10243, in which the V-faces of the metal element receiving the load from the pulley can be moved in parallel by devising the shape of a pair of left and right recesses formed in a lower edge of an element body of the metal element and depressed upwards, thereby solving the above-described problem.
To decrease the pitching moment about a locking edge 41xe2x80x2 of a metal element 32xe2x80x2 to stabilize the behavior of the metal element 32xe2x80x2, it is desirable that the center of the V-face 39xe2x80x2 of the metal element 32xe2x80x2, i.e., the center of the load, is located at a point as near as possible to the locking edge 41xe2x80x2 to shorten a moment arm, as shown in FIG. 10A. Therefore, the metal element 32xe2x80x2 shown in FIG. 10C having a smaller V-face height Hvxe2x80x2 is convenient for the purpose of locating the center of the load at the point near the locking edge 41xe2x80x2, as compared with the metal element 32xe2x80x2 having a larger V-face height Hvxe2x80x2 shown in FIG. 10B. However, if the V-face height Hvxe2x80x2 is decreased, the shape of a recess 46xe2x80x2 in the metal element 32xe2x80x2 cannot be determined appropriately, and it is difficult to ensure that the sum total of moments applied to the saddle face 44xe2x80x2 of the metal element is 0 (zero). As a result, the following problem is encountered: the V-faces 39xe2x80x2 of the metal element 32xe2x80x2 are moved in the inclined manner rather than in parallel due to the load received from the pulley, and for this reason, an uneven wearing occurs in the metal element 32xe2x80x2 and the pulley.
The present invention has been accomplished with the above circumstance in view, and it is an object of the present invention to prevent the V-face from being inclined due to the load from the pulley to suppress the uneven wearing of the metal element and the pulley, while decreasing the V-face height of the metal element.
To achieve the above object, according to one embodiment of the present invention, there is provided a belt for a continuously variable transmission, in which a pair of left and right ring slots defined in each of a plurality of metal elements are supported on a pair of left and right metal ring assemblies with each formed of a plurality of endless metal rings laminated one on another, respectively, and which is wound around a drive pulley and a driven pulley to transmit a driving force. The metal element includes a neck provided between the pair of left and right ring slots, an ear integrally connected to an upper portion of the neck, an element body integrally connected to a lower portion of the neck, a pair of left and right saddle faces formed on an upper surface of the element body to support a lower surface of the metal ring assembly, a pair of left and right V-faces which are formed at laterally opposite ends of the element body and contact the V-groove of the pulleys, and a pair of left and right recesses defined in a lower edge of the element body and depressed upwards. A height Hs of a non-contact portion formed at an upper portion of the V-face and spaced apart from the V-groove is set larger than a height Hsxe2x80x3 of a non-contact portion formed at a lower portion of the V-face and spaced apart from the V-groove.
With the above arrangement, the height Hs of the upper non-contact portion of the V-face is set larger than the height Hsxe2x80x3 of the lower non-contact portion of the V-face. Therefore, even if the V-face height Hv is decreased to decrease the pitching moment on the metal element due to the load applied to the V-face, the V-face can be prevented from inclination due to the load to decrease the parallelism, thereby preventing the uneven wearing of the V-face of the metal element and the V-groove of the pulley.
According to another embodiment of the present invention, there is provided a belt for a continuously variable transmission, in which a pair of left and right ring slots defined in each of a plurality of metal elements are supported on a pair of left and right metal ring assemblies with each formed of a plurality of endless metal rings laminated one on another, respectively, and which is wound around a drive pulley and a driven pulley to transmit a driving force. The metal element includes a neck provided between the pair of left and right ring slots, an ear integrally connected to an upper portion of the neck, an element body integrally connected to a lower portion of the neck, a pair of left and right saddle faces formed on an upper surface of the element body to support a lower surface of the metal ring assembly, a pair of left and right V-faces which are formed at laterally opposite ends of the element body and contact the V-groove of the pulleys, and a pair of left and right recesses defined in a lower edge of the element body and depressed upwards. When a height of the V-face is represented by Hv, and a height of a non-contact portion formed at an upper portion of the V-face and spaced apart from the V-groove is represented by Hs, a ratio Hs/Hv is set in a range of 0.149xe2x89xa6Hs/Hvxe2x89xa60.258.
With the above arrangement, the ratio of the height Hs of the upper non-contact portion of the V-face to the height Hv of the V-face is set in the range of 0.149xe2x89xa6Hs/Hvxe2x89xa60.258. Therefore, even if the V-face height Hv is decreased to decrease the pitching moment on the metal element due to the load applied to the V-face, the V-face can be prevented from inclination due to the load to decrease the parallelism, thereby preventing the uneven wearing of the V-face of the metal element and the V-groove of the pulley.
According to another embodiment of the present invention, there is provided a belt for a continuously variable transmission, in which a pair of left and right ring slots defined in each of a plurality of metal elements are supported on a pair of left and right metal ring assemblies with each formed of a plurality of endless metal rings laminated one on another, respectively, and which is wound around a drive pulley and a driven pulley to transmit a driving force. The metal element includes a neck provided between the pair of left and right ring slots, an ear integrally connected to an upper portion of the neck, an element body integrally connected to a lower portion of the neck, a pair of left and right saddle faces formed on an upper surface of the element body to support a lower surface of the metal ring assembly, a pair of left and right V-faces which are formed at laterally opposite ends of the element body and contact the V-groove of the pulleys, and a pair of left and right recesses defined in a lower edge of the element body and depressed upwards. When a height of the V-face is represented by Hv (mm), and a height of a non-contact portion formed at an upper portion of the V-face and spaced apart from the V-groove is represented by Hs (mm), a relationship,
xe2x88x920.5265Hv+2.768xe2x89xa6Hsxe2x89xa6xe2x88x920.5934Hv +3.524
is established.
A skilled artisan would appreciate that, for example, the term xe2x80x9cxe2x88x920.5265 Hvxe2x80x9d means xe2x88x920.5265 multiplied by Hv.
With the above arrangement, the relationship between the V-face height Hv (mm) and the height Hs (mm) of the upper non-contact portion of the V-face satisfies the relationship,
xe2x88x920.5265Hv+2.768xe2x89xa6Hsxe2x89xa6xe2x88x920.5934Hv+3.524.
Therefore, even if the V-face height Hv is decreased to decrease the pitching moment on the metal element due to the load applied to the V-face, the V-face can be prevented from inclining due to the load to decrease the parallelism, thereby preventing the uneven wearing of the V-face of the metal element and the V-groove of the pulley.
According to another embodiment of the present invention, a plurality of oil grooves are defined in the V-face.
With the above arrangement, a required amount of oil can be retained between the V-face of the metal element and the V-groove of the pulley, and an extra amount of oil can be discharged promptly, thereby stabilizing the coefficient of friction between the V-face and the V-groove.